Overview Of Radio Resource Management; Radio Resource Monitoring; Transmit Power Control - Cisco 2100 Series Configuration Manual

Overview of Radio Resource Management

Overview of Radio Resource Management
The radio resource management (RRM) software embedded in the controller acts as a built-in RF
engineer to consistently provide real-time RF management of your wireless network. RRM enables
controllers to continually monitor their associated lightweight access points for the following
information:
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Using this information, RRM can periodically reconfigure the 802.11 RF network for best efficiency. To
do this, RRM performs these functions:
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Radio Resource Monitoring

RRM automatically detects and configures new controllers and lightweight access points as they are
added to the network. It then automatically adjusts associated and nearby lightweight access points to
optimize coverage and capacity.
Lightweight access points can simultaneously scan all valid 802.11a/b/g channels for the country of
operation as well as for channels available in other locations. The access points go "off-channel" for a
period not greater than 60 ms to monitor these channels for noise and interference. Packets collected
during this time are analyzed to detect rogue access points, rogue clients, ad-hoc clients, and interfering
access points.
In the presence of voice traffic (in the last 100 ms), the access points defer off-channel measurements.
Note
Each access point spends only 0.2 percent of its time off-channel. This activity is distributed across all
access points so that adjacent access points are not scanning at the same time, which could adversely
affect wireless LAN performance. In this way, administrators gain the perspective of every access point,
thereby increasing network visibility.

Transmit Power Control

The controller dynamically controls access point transmit power based on real-time wireless LAN
conditions. Normally, power can be kept low to gain extra capacity and reduce interference. The
controller attempts to balance the access points' transmit power according to how the access points are
seen by their third strongest neighbor.
Cisco Wireless LAN Controller Configuration Guide
11-2
Traffic load—The total bandwidth used for transmitting and receiving traffic. It enables wireless
LAN managers to track and plan network growth ahead of client demand.
Interference—The amount of traffic coming from other 802.11 sources.
Noise—The amount of non-802.11 traffic that is interfering with the currently assigned channel.
Coverage—The received signal strength (RSSI) and signal-to-noise ratio (SNR) for all connected
clients.
Other —The number of nearby access points.
Radio resource monitoring
Transmit power control
Dynamic channel assignment
Coverage hole detection and correction
Chapter 11 Configuring Radio Resource ManagementWireless Device Access
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